In response to the question “how big you do print”, I provided this (for me, unusually non-technical) answer:
I have an Epson 4900 and a 9800, so the largest print I can make at home is 44 inches wide, less three or four inches for the border. I’ve made 36×52 prints from a Nikon D3, which has about the resolution of the a7S. Viewed from a distance, they were fine.
I’ve sent out files for 60×60 prints, but they were on canvas, which doesn’t show details very well, and they were from Betterlight Super 6K files, so I had plenty of pixels. I would feel fine about printing a7RII files that big, even with the cropping that format implies, if they didn’t have to stand nose-to-print inspection.
I normally print a7II and a7RII files on C-sized (17×22 inch) paper, with one-inch margins.
If the viewing distance is restricted, there’s really no limit to how large prints you can make, except the printer and post-print stitching limitations. Billboards are an example. Another example from the old days, was the Kodak Colorama that rotated pictures for years in NYC’s Grand Central Station:
At 18×60 feet, the images were immense. Some of the later ones were made from originals consisting of 35mm transparencies and negatives, although they started out with 8×10 cameras.